1. Field of the Invention
This invention relates to endophytic fungi, to plants infected with the fungi, to a method of introducing endophytic fungi into the plants and to methods for planting the infected plants, where the endophytic fungi improve the plant's tolerance to environmental stresses and reduce or eliminate the production of agents that are toxic to livestock or other grazing animals.
More particularly, this invention relates to endophytic fungi of the genus Neotyphodium that when artificially introduced into a plant improve the plant's tolerance to environmental stresses while rendering the plant substantially non-toxic to livestock or other grazing animals, to plants infected or inoculated with the fungi, to a method of introducing the endophytic fungi into plants and to methods for replacing existing forage plant species and varieties with the new drought tolerant, non-toxic endophyte infected varieties.
2. Description of the Related Art
Grasses, tall fescues and other related species in the genera Festuca, Lolium and their hybrids are often a food source for grazing animals. Such vegetation are typically not sufficiently tolerant to environmental stresses such as drought, drought and excess heat or other forms of water or heat stress to be used in many arid or semi-arid or hot climes. Typically, these grasses, fescues or other related species occur in the wild, and these plants occur, with high frequency, in nature infected with filamentous internal fungi, i.e., endophytes. These endophytes grow particularly well in the gaps between cells, i.e., the intercellular spaces. These endophytes, or symbiotic filamentous fungi, do not adversely affect the host plant and can provide the plant with useful substances, improve the plant's tolerance of environmental stresses, and deter feeding on the plants by mammals, insects, and nematodes.
Enhancement by endophytes are known to impart the following properties to their host plants: insect resistance (Siegel et al, 1987 Ann. Rev. Phytopathol. 25:293-315); disease resistance (Gwinn and Gavin, 1992,Plant Disease 76:911-914); environmental stress (drought, etc.) resistance (Arachevalta et al, 1989 Agron J. 81:83-90), and growth enhancement (Latch et al, 1985, N.Z.J Agric. Res. 28:165-168). Moreover, endophyte-infected perennial ryegrasses have improved insect resistance due to certain alkaloids produced by the endophyte.
Although certain endophytes have been identified that impart useful traits to their host plants, it would represent an advancement in the art to have available to industries that utilize grasses, fescues and other similar plant life, endophytes that stably infect such plants and impart good tolerance to environmental stresses and reduced production of substances toxic to livestock or other grazing animals.